I have tried lots of stuff to get the VX to get better MPG and I have found that i can get 19 if I don't drive to sparatackly on the highway and use the cruise a lot. also what helped is changing to synthetic fluids in everything tranny, engine, differentials, and TOD, plus the grease on the proppeller shaft. I also noticed that if I am using 5w 30 synthetic engine oil that helps, but I have heard not to use that weight when the temperature is going to be close to 100. I now have a SC and with that plus all the other stuff I have done, I normaly get between 19 and 21 if I drive concervitavely. Also every time I change my oil I use a motor flush I think mine is from Gunk or liquid wrench.